15A-3 |
Optimized synthesis of lipase-catalyzed hexyl butyrate with lipase IM77 by response surface methodology |
C. J. SHIEH1, S. W. Chang, and J. R. Too. (1) Dept. of Food Engineering, Dayeh Univ., 112 Shan-Jiau Rd., Datsuen, Changhua, 51505, Taiwan Hexyl butyrate is an extremely aroma compound with green notes flavor and wildly used in food industry. It can be isolated from natural sources or produced by chemical synthesis. However, the biosynthesis of such esters by lipase-catalyzed chemical reactions under mild conditions became much current commercial interest. The present work focuses on the reaction parameters that affect lipase from Mucor miehei (Lipozyme IM-77)-catalyzed transesterification of hexyl butyrate using tributyrin as acyl donor in n-hexane. Our purposes were to better understand relationships between the factors and the response; and to determine the optimal conditions and procedure for hexyl butyrate synthesis using central composite rotatable design (CCRD) and response surface methodology (RSM) analysis. Hexanol (100 mM) and different molar ratios of tributyrin were added to 3 mL n-hexane, followed by different amounts of added water and enzyme. Triacetin (50 mM) was employed as an internal standard. The analyses of samples were performed by Hewlett Packard 4890 GC equipped with FID and DB-5 fused-silica capillary column. RSM and 5-level-5-factor CCRD were employed to evaluate the effects of synthesis parameters, such as reaction time (2 to 10 h), temperature (25 to 65 ¢XC), enzyme amount (10 to 50%), substrate molar ratio of tributyrin to hexanol (1:1 to 3:1), and added water content (0 to 20%) on percentage molar conversion of hexyl butyrate by transesterification. Our results showed that reaction time and temperature were the most important variables for hexyl butyrate synthesis. Based on the canonical analysis, the optimum synthesis conditions were: reaction time 8.3 h, temperature 50.3 ¢XC, enzyme amount 42.7%, substrate molar ratio 1.8:1, and added water 12.6%. The predicted value was 96.2% and actual experimental value 95.3% molar conversion. The optimized enzymatic synthesis for hexyl butyrate by lipase IM-77 was successfully developed by CCRD and RSM.
Session 15A, Biotechnology
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